Workpiece conveying devices are used for conveying workpieces in tandem press lines for successively pressing workpieces.
There are various workpiece conveying devices of robot style provided with arms.
For instance, there is known a workpiece conveying device comprising a beam built between adjoining press machines, a carrier provided to be freely movable along the beam, a cradle table supported by the carrier and being driven to swing along a workpiece conveying direction, and a crossbar suspending and supporting a workpiece via vacuum cups holding the workpiece in a freely detachable manner, wherein a relative distance between a swing center of the cradle table and the crossbar is arranged to be variable by providing a field lever at the cradle table via a linear moving mechanism (see, for instance, Patent Literatures 2 and 3).
Further, there is known a workpiece conveying device comprising a workpiece holding means which holds a workpiece, a carrier disposed between adjoining presses and being linearly movable in a direction orthogonal to a workpiece conveying direction by means of a driving mechanism, and a swinging body which central axis of swinging is provided at the carrier and which is driven to swing along the work conveying direction by means of a swinging mechanism (for instance, Patent Literature 4).
In this workpiece conveying device, there is provided a so-called Scott Russell mechanism in which an inter-axial distance of both ends of a second link is defined to be half of an inter-axial distance of both ends of a first link, and in which one end of the second link is coupled to a center of the axis interval of both ends of the first link while the other end of the second link is positioned on an extension of a moving line of another end of the first link.